Nvidia’s Tegra 4 demystified: 28nm, 72-core GPU, integrated LTE, and questionable power consumption
Nvidia’s launch party last night contained some significant data on Tegra 4 over and beyond what the company discussed for its new gaming handheld. There weren’t many surprises on a hardware level: Tegra 4 is a quad-core Cortex-A15 with a fifth Companion Core for low-power operation, an integrated Icera LTE/WCDMA softmodem, and a new camera technology that leverages its programmable GPU.
Technical details on the GPU sadly aren’t available yet — the only chip Jen-Hsun discussed was the G80 (Nvidia’s first programmable GPU). We know Tegra 4 has 72 GPU cores, and that they’re programmable and CUDA-compatible. Presumably the Tegra 4 GPU is based on Kepler-level technology. Tegra 4 itself will be built on TSMC’s 28nm HPL (low-power) process, and the total die size is around 80mm. The CPU cores will be capable of hitting 1.9GHz, though it remains to be seen how fast Tegra 4 will actually be clocked in smartphones.
Tegra 4 is the first major evolution of the company’s mobile GPU capabilities, but you wouldn’t have known that to judge by last night’s demo. The company fumbled its way through meandering product discussions and weak demos. Non-Shield game performance looked good, but not extraordinary. The demo of Dead Trigger 2 showed major frame rate dips as on-screen action intensified. During the Project Shield game demos, Huang made repeated reference to “driving” a 4K television from stage, despite the fact that the handheld obviously wasn’t pushing 4,000 horizontal pixels.
Tegra 4′s Icera LTE softmodemThe new i500 software modem contains a block of eight programmable processors. Jen-Hsun made a huge deal about the modem’s capability — 1.2 trillion operations per second — but then claimed this was a fundamental feat of computing that a modern Core i7 from Intel couldn’t match, even with a 77W TDP. As an IT journalist, this sort of mismatched comparison is deeply frustrating. It’s not that Jen-Hsun is wrong, per se — it’s that the two devices aren’t comparable.
Nvidia claims that the Icera softmodem approach saves a great deal of die space compared to a hardware radio, but die size isn’t going to be the only consideration. 4G/3G/WiFi radios consume a significant percentage of a smartphone or tablet’s power budget. There are only a handful of smartphones on the market that use Icera’s softmodem tech and none of them have decent battery life.
As far as technical details go, the i500 will be capable of category 3 LTE (100Mbps), WCDMA, HSPA+, EDGE, and GSM. VoLTE is supported as well. Support for category 4 LTE will be added later, via a software update (one of the neater aspects of a softmodem). The i500 will be built on TSMC’s 28nm HP HKMG process.
Tegra 4 camera techThe last major unveil was Tegra 4′s camera. First, Huang trotted out an iPhone 5 image that supposedly highlights the camera’s shortcomings when shooting in daylight and in HDR mode. I don’t have an iPhone 5 to compare against, but I’ve seen similar blurring when shooting a moving target with HDR enabled.
Standard mode on the left, HDR on the right. Images by NvidiaAccording to NV, current image processing looks something like this:
Where’s Tegra 4 does things like this:
Comic sans has a new competitor for the worst font everTegra 4 can do real-time HDR previews and apply the effect as a filter. To demonstrate, Huang brought up a booth babe and pretended to be meeting her at a Tahiti tiki bar. It’s hard to imagine a more awkward demonstration. Huang joked that the woman was far prettier than your average gamer and forced her to pointlessly demonstrate her gaming chops by listing several titles she enjoyed playing. The two of them then posed for a photo against a beach backdrop under full spotlights.
The entire affair came off as a ham-fisted attempt to curry favor, and distracted from Tegra 4′s actual capabilities. The camera technology actually looks pretty good and the real-time filter is a nice touch. Obviously lens choices and flash quality will also impact the camera’s overall performance, but NV is clearly moving the bar here.
Power consumptionNV hasn’t detailed Tegra 4′s power consumption yet, but Jen-Hsun did give some details on Shield’s battery capacity and battery life. The handheld contains three 3.7V lithium-ion batteries with a total capacity of 37.74 (38) watt-hours. According to the CEO, that’s enough juice for 5-10 hours of gaming. This points to device level power consumption of roughly 4-8W. That’s far more than either the Vita or the 3DS, and about on par with what you’d find inside a Retina iPad.
What this suggests is that NV doesn’t have a ready-made solution to the Cortex-A15′s power consumption issues. There’s no word yet on price, availability, or independently verified performance figures.
Based on what we’ve seen thus far, I think Tegra 4 is a big step forward for Nvidia. Outside of Project Shield and the difficulty of launching a new handheld gaming device, I think it’s positioned to do well. Clock speeds, power consumption, and the Icera softmodem’s performance characteristics will play a major role in determining just how much momentum NV can build for its latest creation. Qualcomm nor Intel are going to be sitting still, though.
source:extremetech
